1. Field of the Invention
The present invention relates to an ad-hoc network, and more particularly, to a method for assigning an address to a node of the ad-hoc network upon being requested by the node.
2. Description of the Related Art
In a general mobile communication system, a mobile element transmits and receives data to and from a base station. The mobile element and the base station directly transmits and receive data to and from each other without relaying the data to another node. In an ad-hoc network, however, when a source node transmits data to a destination node, it uses another node to transmit the data to the destination node.
The ad-hoc network is a self-configuring network of mobile nodes. The nodes are free to move randomly, and thus, the ad-hoc network changes rapidly and unpredictably. In the ad-hoc network, the nodes are communicable with each other without being supported by an existing mobile communication system, and have no limitation in a communication range if supported by multiple hops.
For various applications of the ad-hoc network, methods for connecting with a server (Internet) have been discussed. Among them, a method of connecting the ad-hoc network to the server using an Internet gateway (IG) has been currently discussed.
FIG. 1 is a view showing a conventional ad-hoc network 100, a router 120, a server 130 and an IG 110 connecting the ad-hoc network 100 and the router 120.
The ad-hoc network 100 consists of a plurality of nodes. For example, as shown in FIG. 1, the ad-hoc network 100 consists of nodes 1 to 7. The nodes 1 to 7 are connected with the IG 110 through a wireless network, and the IG 110 is connected to the server 130 via the router 120. The IG 110 transmits data received from the nodes 1 to 7 to the server 130 and also transmits data received from the server 130 to the nodes 1 to 7.
In order to communicate with the IG 110, the nodes 1 to 7 of the ad-hoc network 100 each has to be assigned with an address from the IG 110. The IG 110 selects one of assignable addresses when being requested for the address assignment from the nodes 1 to 7, and transmits the selected addresses to the requesting node. The address assigned from the IG 110 is usable only in the ad-hoc network. This means that the address is a local address. Suppose that the same local address is used at least two ad-hoc networks. When two nodes are assigned with the same local address and communicate with the server 130, the server 130 cannot distinguish the two nodes.
As described above, the ad-hoc network 100 consists of the plurality of nodes 1 to 7, and the IG 110 assigns an address to a node requesting for address assignment. Since the nodes are free to move in the ad-hoc network 100, the nodes may request the IG 110 for the address assignment at the same time. In this case, the IG 110 has to respond to the all requests for the address assignment from the nodes. Simultaneously, the IG 110 has to relay data between the nodes of the ad-hoc network 100 and the server 130. However, since the IG 110 performs the address assignment function and the data relaying function simultaneously, it is very likely subjected to an excessive load. Accordingly, a method for reducing the load exerted to the IG 110 has been demanded.